Abstract:
محدودیت منابع آب از یکسو و افزایش تقاضای روزافزون آن از سوی دیگر مسأله تخصیص را بیش از پیش مهم جلوه میدهد. تخصیص اغلب موارد شامل بحثهای چندین گروه با نیازها و وضعیتهای مختلف اجتماعی، اقتصادی و سیاسی میباشد. لذا بایستی راه حل مدیریتی برای گستره وسیعی از تقاضاها ارائه گردد. هدف این تحقیق، ارائه الگویی برای بهینه کردن تخصیص و مصارف آب شرب و کشاورزی اراضی بالادست و پاییندست دشت چغلوندی در استان لرستان با استفاده از مدل WEAP است. شبیهسازی حوضه برای سه سناریوی: شرایط موجود، سناریوی مرجع و توسعه اراضی کشاورزی انجام گردید. سناریوی شرایط موجود آنچه در وضعیت حال حاضر در دشت است؛ سناریوی مرجع افزایش جمعیت برای افق 16 ساله و ثابت ماندن دیگر اما با اولویت نیاز شرب و صنعت در اول و سایر نیازهای زیست محیطی و کشاورزی در اولویتهای دوم و سوم و سناریوی سوم توسعه اراضی کشاورزی پایین دست سد ایوشان افزایش سطح اراضی از 2500 هکتار به 5300 هکتار. از مقایسه سناریوها مشاهده شد که سناریوی مرجع نسبت به سناریوی توسعه اراضی حجم ذخیره مخزن کمتر با شکست مواجه خواهد شد و ضریب اطمینانپذیری شبکههای آبیاری و زهکشی در شبکه-های آبیاری و زهکشی چغلوندی، پایین دست سد و یسیان در هر دو سناریوی 100 درصد و در شبکه آبیاری و زهکشی دولیسان در سناریوی توسعه اراضی تأمین آب با افزایش سطح زیر کشت کاهش مییابد. نتایج نشان داد که نیاز زیستمحیطی منطقه در این شرایط در ماههای فروردین و اردیبهشت در طول دوره شبیهسازی حدود 10% کمتر از حد مجاز تأمین شده و این برای ماههای بهار که بایستی حدود60% باشد نامطلوب میباشد.
IntroductionIntegrated exploitation using the scenario method can increase the reliability of using water resources in the presence of uncertainties. One of the most important challenges of exploiting water resource management systems and specifically surface reservoirs in facing hydrological changes is to consider the occurrence of drought in the way of exploiting water resources. In addition to the changes in discharge compared to the average, another important factor is the continuation of the drought phenomenon. One of the ways to deal with drought is the proper use of water resources in drought conditions. Various models such as WEAP have been developed to exploit water resources. But such a model does not have the ability to model the exploitation of reservoirs in drought conditions. Therefore, developing such a possibility in the WEAP model is very important for water resources engineers. Considering the development of the WEAP model as a tool for flexible, comprehensive and transparent planning in evaluating the various long-term conditions of the basin, this model has been used to simulate the water resources of the basin and develop different scenarios for the exploitation of water resources.Materials and Methods The scenarios are made in the existing conditions and by using them, the effect of different assumptions or policies on the availability and consumption of water in the future can be checked. Finally, the scenarios are evaluated according to the amount of water, costs and benefits, compatibility with environmental goals and sensitivity to uncertainty in key variables. In the WEAP model, system components (including nodes of water resources and uses, how they are related to each other and allocation priorities) and the introduction of time characteristics (base year, time period, time steps of calculations, etc.) are defined. In the base year, water needs, capacity and characteristics of resources, pollution loads, system costs in the current state are entered. By initially running the model in the base year and comparing the results with the available information, this step can be considered as a calibration step. In the scenario development section, a set of assumptions related to the impact of any changes in the system (due to changes in policies in the future or climatic conditions) are defined. According to the user's desired criteria, the scenarios are evaluated at this stage. These criteria can be reliability in meeting needs, resource protection, compatibility with environmental goals, benefit and cost analysis, and sensitivity to uncertainties in key variables. To prepare the main framework of the model in the WEAP software, first, the basic maps that include the borders of the studied basin, the routes of the rivers in the basin, the location of dams and diversion dams for water intake and hydrometric stations, all the points of need and available water resources and in general all the tolls which is needed to determine the main framework of the model was prepared in the GIS environment. After this work, the prepared maps were called in the WEAP software environment. Using the tools available in the WEAP software, the route of the main river, the location of the Ivshan dam, underground water sources, the location of drinking water needs and industry, agriculture and all the required items were determined.Results and Discussion The degree of simulation correlation is simulated in maximum values with a small time difference and in some places the values are lower than the observed values. Based on the existing conditions, the monthly amounts of agricultural needs were simulated for each network. Based on this diagram and the reliability percentage diagram, it can be seen that the needs are 100% provided except for the Dolisan range in every month. Reliability or reliability, in fact, means the probability that the system will perform the assigned tasks without failure, this value has been obtained. For this scenario, it can be seen that the amount of water withdrawal for drinking and industry and the irrigation networks downstream of the Ivshan dam is 100%, and the irrigation networks of the two aquifers of Chaglundi and Yesian are 100%, and for Dolisan agriculture is less than 80% was achieved by first providing surface water sources (Herod River) and then underground water. From the results of the first scenario for the environmental needs of the region, it can be seen that in the months of April and May, during the simulation period, for the months of spring, which should be around 60%, around 10% less than the allowed limit is provided, and this is undesirable. In a study conducted in the Lifan Basin in South Africa using the WEAP model to simulate and analyze its allocation scenarios, it was observed that 85% of the water demand was provided under the existing conditions.Conclusion The results of the calibration performed for the model in the simulation period from 2012 to 2019 for the Ivshan Dam showed that the simulation of water resources exploitation of the study basin using the WEAP model was done with appropriate accuracy and the performance has had a good The results of the evaluation of the scenarios showed that in the scenario of the existing conditions, due to the limitation created by the relevant bodies in allocating water to a limited area of the covered plain, the reliability coefficient for drinking and irrigation and drainage networks is 100%. and the environmental needs of the region under these conditions in the months of April and May during the simulation period were provided about 10% less than the allowed limit and this is undesirable for the spring months which should be around 60%. In the reference scenario, despite the population increase in the coming years, due to setting the first priority in the allocation to drinking consumption in the simulation model, the need for drinking and industry will be fully provided. The agricultural needs in the irrigation networks downstream of the studied dam are 100% provided in all months, but the agricultural needs supplied from the Dolisan Plain aquifer in all months were less than 60% of the water needs. The minimum environmental requirement of the lower reaches of Herod River, which is considered for the survival of the region's ecosystem, is less than 50% in the spring months and is significant.